J. Phys. I France
Volume 6, Number 12, December 1996
Page(s) 2135 - 2140
DOI: 10.1051/jp1:1996208
J. Phys. I France 6 (1996) 2135-2140

Dielectric Voltage Response in Spin-density Wave of (TMTSF) $\mathsf{_2}$AsF $\mathsf{_6}$ at Low Temperature

Mitsuharu Nagasawa

Department of Physics, Hokkaido University, Sapporo 060, Japan

(Received 26 April 1996, revised 19 August 1996, accepted 20 August 1996)

Voltage response to constant unipolar pulse current in the spin-density wave (SDW) state of (TMTSF) 2AsF 6 was studied. Below 3 K, leading and tailing edges of the voltage response are rounded at low electric field. The time dependent charge density accumulated in the lattice was estimated from the voltage profiles. It can be fitted by a stretched exponential formula; $q(t)\propto q_0 (1-{\rm exp}(-(t/\tau_1)^\beta))$. With increasing field q0 increases and shows a maximum at the threshold electric field for depinning. In the pinned state, the relaxation time $\tau_1$ increases with decreasing temperature and its activation energy is approximately equal to that of ohmic conductivity. The index $\beta$ is a linearly decreasing function of temperature and it is extrapolated to one at 0 K. Screening by normal carriers becomes imperfect and coupling between density wave domains becomes stronger on cooling.

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